Multidrug-resistant tuberculosis in a low-incidence region shows a high rate of transmission.

Objective: To describe the characteristics of patients with multidrug-resistant tuberculosis (MDR-TB), a descriptive prospective study was carried out applying a combination of exhaustive conventional epidemiology with molecular genotyping.
Setting: All patients diagnosed with MDR-TB in Galicia, Spain, between 1998 and 2004 were included in the study.
Design: Of 9895 diagnosed cases of TB, 58 were MDR-TB (0.59%). The site of disease was pulmonary in 56 cases and 46 were smear-positive. Only two cases were co-infected with the human immunodeficiency virus (HIV) and seven were immigrants. Twenty-five (43%) had received previous TB treatment. These cases presented more risk factors for treatment default and a lower frequency of contact with cases of MDR-TB.
Results: Genotyping analysis was performed in 57 patients, showing evidence of four clusters (30 patients, 52.6%), each with identical genetic patterns. The patients included in the clusters were younger, and most had primary forms or had had contact with another case of MDR-TB, especially in hospital. Neither the Beijing/W nor the B strain was identified.
Conclusion: There is a low prevalence of MDR-TB in Galicia. Unlike previous studies, there was a high rate of transmissibility, including nosocomial transmission. Transmission is not associated with HIV or previously reported strains with a high capacity for transmission.